Certain technologies for extracting isoprene from a C5 hydrocarbon mixture and/or butadiene from a C4 hydrocarbon mixture are known in the art. For example, U.S. Pat. No. 6,395,953 and U.S. Patent Publication No. 2008/0257711 disclose a process for producing a purified conjugated diene (e.g., isoprene or butadiene) from a petroleum fraction (e.g., a C4 hydrocarbon fraction or C5 hydrocarbon fraction) by extractive distillation. U.S. Pat. No. 4,310,388 describes a process for isolating a conjugated diolefin from a C4- or C5-hydrocarbon mixture by extractive distillation with the aid of a selective solvent. U.S. Pat. No. 3,692,861 discloses a process for separating and purifying isoprene from a C5 hydrocarbon fraction. U.S. Pat. No. 3,436,438 discloses a process of removing acetylenes from a hydrocarbon mixture containing conjugated diolefins (e.g., isoprene or 1,3-butadiene) by using a solvent.
Two or more extraction systems can be required to extract both butadiene and isoprene, with resulting increases in capital cost, utilities, and land usage.
There remains a need in the art for a co-extraction system that can extract both butadiene and isoprene in one system rather than separate systems.